Fig. 6

Nerve-induced acetylcholine receptor clustering is impaired in muscle from MND patients. A–F Sample visual fields showing human myotube cultures innervated by H9 human axons labeled for neurofilament-SV2 (red-pink) and AChRs clusters (green). Three paired sets of non-MND versus MND muscle cells (matched for sex and approximate age) are compared (A vs B, C vs D, E vs F). Insets (A′, B′, C′, D′, E and F′) show the AChR clusters indicated by arrows at higher magnification. Dotted white lines indicate the edge of the myotubes. White arrows in A′, C′ and E′ indicate large AChR clusters proximal to NF-SV2 labeled motor axons. Yellow arrows in B′, and D′ indicate small AChR clusters close to NF-SV2 labeled motor axons. Yellow arrows in F′ show large AChR clusters close to NF-SV2 labeled motor axons. Scale bars for A–F = 40 µm, and for A′–F′ = 20 µm. G Quantitation of the area of AChR clusters, expressed as a fraction of the total area of axons averaged from 3 visual fields per MN-muscle sample, as per [56]. H Frequency histogram showing a significantly greater number of large AChR clusters (> 25 µm²) on myotubes of control cultures compared to MND cultures (n = 3 patients). I Total area of AChR clustering (large plus small clusters) per microscope field. Data points show results from individual data presented in G, (n = 3 patients). Data presented as mean ± SD. For H, data was analyzed using two-way ANOVA, followed by Bonferroni’s multiple comparisons test (**p ≤ 0.01)